This grant is the biological part of a colaborative study of the psychobiology of depression. There is a biological part and a separately numbered and funded clinical part. The biological part is obtaining information on patients with primary affective disorder and as comparison groups, other psychiatrically ill patients, and normal controls. The chemical constituents measured include plasma levels of tricyclic antidepressants, spinal fluid levels of HVA, HIAA and MHPG. MHPG levels will also be measured in plasma of treated (with amitriptyline or imipramine) and untreated patients. There will also be an insulin tolerance test to establish growth hormone dynamics, and a dexamethasone suppression test to test the hypothalamic pituitary axis. The intention is to have approximately 300 subjects and controls so that there will be a large enough sample from which to make inferences concerning the meanings of the biological results found.